A cured product of the epoxy resin has excellent properties such as size stability, mechanical strength, electrical insulation, heat resistance, water resistance, chemical resistance and the like. However, there are problems that the cured product of the epoxy resin has a very fragile property such as a small fracture toughness, and problems are produced by this property in a wide application in some cases.
Patent Document 1 discloses a technique that polymer fine particles having a core-shell structure are dispersed in a curable resin composition containing as a main component a curable resin such as an epoxy resin.
An adhesive containing the epoxy resin composition having toughness and impact resistance has been used as a structure adhesive for vehicle, and particularly, impact peel-resistant adhesion described in ISO11343 is considered to be important, so that the improvement of impact peel-resistant adhesion has been required in the curable resin composition. In addition, Patent Documents 2 and 3 disclose techniques that polymer fine particles having a core-shell structure in which a core layer contains diene rubber and a shell layer contains at least hydroxyl group are dispersed in a curable resin composition containing as a main component a polyol using in the formation of polyurethane and the like.
In addition, Patent Document 4 discloses that polymer fine particles having a core-shell structure and a strengthening agent other than polymer fine particles having the core shell structure are compounded to an adhesive composition containing as a main component an epoxy resin to improve impact peel-resistant adhesion.